1. Field of the Invention
The present invention relates to a method of fabricating a via hole and a trench and, more particularly, to a method of fabricating a via hole and a trench which removes oxygen of a copper oxide layer by using Hf.
2. Background of the Related Art
FIG. 1 is a cross-sectional view illustrating process of fabricating a via hole and a trench by using a damascene process according to the prior art.
Referring to FIG. 1, a copper interconnect 12 is formed on a substrate 11 on which a predetermined device is formed. After an interlayer dielectric layer 13 is deposited on the copper interconnect 12, it is patterned by using a damascene method to expose some part of the copper interconnect 12. A barrier layer 14, which is made of Ta, TaN or both, is then formed. The reason the barrier layer 14 is made of Ta, TaN or both is that they have a better characteristic than Ti and TiN in terms of the prevention of copper diffusion. The copper interconnect 12 should be cleaned prior to the formation of the barrier layer 14 so as to prevent the formation of impurities such as copper oxide, which results from exposure of the surface of the lower copper layer connected to a via hole to the air. In order to remove the copper oxide which causes high via resistance, dry cleaning by plasma or wet cleaning by etching solutions is conducted. After the deposition of the barrier layer 14, copper filling 15 is carried out. As described above, the prior art has a problem that one additional process of removing copper oxide is required. Moreover, as wet cleaning for removing copper oxides unintentionally damages the interlayer dielectric layer, critical dimension(hereinafter referred to as “CD”) of the interlayer dielectric layer is affected, so that step coverage during the barrier layer formation process becomes deteriorated. Furthermore, because the wet cleaning radially etches the copper interconnect itself as well as the copper oxide, much deposition of the barrier layer is necessary, and bottom coverage becomes deteriorated.